This invention relates to the measurement of a flux of neutrons at a desired location such as the interior of a nuclear reactor.
The monitoring and control of a nuclear reactor requires a knowledge of the neutron flux at particular locations in the interior of a nuclear reactor. It is necessary to cause the uncharged neutrons to impinge upon some type of device which generates from their flux a signal which is either an electrical signal or which is convertible into an electrical signal for remote amplification and detection. Various types of detectors such as ionization chambers have been used in the past to generate electrical signals from ion fluxes. Of particular utility is a solid-state detection device made of a ceramic such as magnesium oxide or aluminum oxide. The ceramic may be in either solid or powdered form. A flux of neutrons incident on such a ceramic will generate charged particles and gamma rays as a result of the collisions of neutrons with the atoms of the ceramic. By selection of the materials of the ceramic it is possible to effect desired forms of discrimination against unwanted energy ranges in the neutron flux. However, the price that is paid for this advantage is the extremely low level of the signal that is generated by the incidence of a particular neutron on the ceramic. Because this signal occurs at a low level, it is necessary to take steps to insure that the signal not be lost in any electrical noise that is generated elsewhere in the system.
A further problem arises from the fact that the information about the neutron flux at a particular location in a reactor must be transmitted to a remote location to be of any use. This means that some form of electrical cabling is used to connect from the location of the detector within the reactor to the electrical logical and processing apparatus located outside the reactor. Typically at least a portion of the cable connecting these two will be exposed to a portion of the neutron flux existing in the interior of the reactor. This flux will generate signals in the cable which comprise an interfering electrical noise component that tends to mask the desired signals generated by neutrons incident upon the detector. This problem is compounded by the fact that the flux of neutrons is a random process obeying statistical laws and can therefore be separated from interfering signals only by the use of statistical techniques.
It is an object of the present invention to provide a better means of detecting a flux of neutrons.
It is a further object of the present invention to facilitate the use of solid-state neutron detectors for detecting a flux of neutrons.
It is a further object of the present invention to provide a means of separating the electrical signals resulting from the incidence of a flux of neutrons on a detector from the interfering electrical noise resulting from the incidence of neutrons on the cables connecting the neutron detector to external electrical signal processing equipment.
Other objects will become apparent in the course of a detailed description of the invention.